A device of this type has been disclosed in EP 0 886 184, wherein a vacuum-operated device is described which is arranged between a wafer and an optical element. The device has an illumination field opening at its center, leaving a minimal upper gap to a lens surface and a further minimal gap to a wafer surface. The gas flow is introduced above and below the device and exits again within the device through slot-shaped openings. As a result, contaminations, specifically dust grains, are removed from the lens surface.
The task that has been set for the present invention is to provide a device which can be arranged in the critical areas of the projection apparatus but dues not absorb a large portion of, nor interfere with, the radiation that is present in those areas.